From patchwork Tue Jun 12 00:32:23 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laura Abbott X-Patchwork-Id: 10459023 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8229060348 for ; Tue, 12 Jun 2018 00:33:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7023127EED for ; Tue, 12 Jun 2018 00:33:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 64A2627F98; Tue, 12 Jun 2018 00:33:26 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 15B2427EED for ; Tue, 12 Jun 2018 00:33:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934843AbeFLAdT (ORCPT ); Mon, 11 Jun 2018 20:33:19 -0400 Received: from mail-pl0-f67.google.com ([209.85.160.67]:39858 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934801AbeFLAcw (ORCPT ); Mon, 11 Jun 2018 20:32:52 -0400 Received: by mail-pl0-f67.google.com with SMTP id f1-v6so13309027plt.6 for ; Mon, 11 Jun 2018 17:32:52 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Rgx81okqi/dPGjCxYFjeGB9OoHrzfYU2VBaGw23rhug=; b=uiaB66pIxaUuwYNcNhaKrmU9RzakJcUSE0mJptWMLOaxTzmMhoMXxKQQv3TlugTBN5 gTveesM8RbL4Ev+Cf+zWI44H8pxl8BX58OwP0gYTSBQOqc4751VOBO5IpfR8W3hj2x0F 2aNOU7L4VUIN0NkxCP/by2vdVQTgKExuMAYYHrX2auMFLUXD2Z4d3n5PqInPZB8k1n3o MZMUK0Y0M2eUYx3j69rGViz4/MOnM7RIqYUyJ5YBV/FrcfxXM2hyCUOvETRzGmc1fKUg K0WVN4Ni1pHVY97AVmBy1zc38hFjQM7U2BYD8siQGl8n/YVfdugySspmxHZNd071hQ93 KO9A== X-Gm-Message-State: APt69E37LQdyCBru8MCRFu5UZlKuX+orzwpCQYamia3OmXRbtSjuYwq7 naSGwB3/9eO+61puwIO44TDXvQ== X-Google-Smtp-Source: ADUXVKKixuYY4A7br4AVxgHvIIdpBNRQLV41p7n/PGvXmCa01UcK0fIZANEljdHXoPMhSDPCwj6QsA== X-Received: by 2002:a17:902:5a3:: with SMTP id f32-v6mr1402338plf.109.1528763572349; Mon, 11 Jun 2018 17:32:52 -0700 (PDT) Received: from localhost.net ([2601:602:9802:a8dc::27e5]) by smtp.gmail.com with ESMTPSA id c12-v6sm40866112pfi.177.2018.06.11.17.32.50 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 11 Jun 2018 17:32:50 -0700 (PDT) From: Laura Abbott To: Andy Lutomirski , mjw@fedoraproject.org, "H . J . Lu" , Masahiro Yamada Cc: Laura Abbott , Linus Torvalds , X86 ML , linux-kernel@vger.kernel.org, Nick Clifton , Cary Coutant , linux-kbuild@vger.kernel.org Subject: [PATCHv4 2/3] kbuild: Introduce build-salt linker section and config option Date: Mon, 11 Jun 2018 17:32:23 -0700 Message-Id: <20180612003224.3658-3-labbott@redhat.com> X-Mailer: git-send-email 2.18.0.rc1 In-Reply-To: <20180612003224.3658-1-labbott@redhat.com> References: <20180612003224.3658-1-labbott@redhat.com> Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The build id generated from --build-id can be generated in several different ways, with the default being the sha1 on the output of the linked file. For distributions, it can be useful to make sure this ID is unique, even if the actual file contents don't change. The easiest way to do this is to insert a section with some data. Introduce a macro to insert a linker section which will be filled with a hex value. This will ensure the build id can be changed just via a config option. Users who don't care about this can leave the default value and strip the section. Suggested-by: Linus Torvalds Signed-off-by: Laura Abbott --- include/asm-generic/vmlinux.lds.h | 6 ++++++ init/Kconfig | 9 +++++++++ scripts/module-common.lds.S | 4 ++++ 3 files changed, 19 insertions(+) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index e373e2e10f6a..4af7e683aad2 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -830,6 +830,12 @@ #define PERCPU_DECRYPTED_SECTION #endif +#define BUILD_SALT \ + . = ALIGN(32); \ + .salt : AT(ADDR(.salt) - LOAD_OFFSET) { \ + LONG(0xffaa5500); \ + . = ALIGN(32); \ + } = CONFIG_BUILD_ID_SALT \ /* * Default discarded sections. diff --git a/init/Kconfig b/init/Kconfig index d2b8b2ea097e..eb92ccfe4ecb 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1967,3 +1967,12 @@ config ARCH_HAS_SYNC_CORE_BEFORE_USERMODE # . config ARCH_HAS_SYSCALL_WRAPPER def_bool n + +config BUILD_ID_SALT + hex "Build ID Salt" + default 0x12345678 + help + The build ID is used to link binaries and their debug info. Setting + this option will use the value in the calculation of the build id. + This is mostly useful for distributions which want to ensure the + build is unique between builds. It's safe to leave the default. diff --git a/scripts/module-common.lds.S b/scripts/module-common.lds.S index d61b9e8678e8..3c8410270ac1 100644 --- a/scripts/module-common.lds.S +++ b/scripts/module-common.lds.S @@ -3,6 +3,9 @@ * Archs are free to supply their own linker scripts. ld will * combine them automatically. */ + +#include + SECTIONS { /DISCARD/ : { *(.discard) @@ -23,4 +26,5 @@ SECTIONS { .init_array 0 : ALIGN(8) { *(SORT(.init_array.*)) *(.init_array) } __jump_table 0 : ALIGN(8) { KEEP(*(__jump_table)) } + BUILD_SALT }